By having unprotected sex, you're risking more than just getting pregnant. STIs such as chlamydia are increasing.

Cases of sexually transmitted infections (STIs), including HIV, are increasing. If you have unprotected sex, your health is at risk. Find out what symptoms to look out for and how to stay safe.

In June 2015, Public Health England released a report on sexually transmitted infections (STIs) in England. The report showed there were 439,243 cases of STIs in 2014. Young people under the age of 25 and men who have sex with men (gay and bisexual) are most at risk of getting STIs.

Public Health England also produce an annual report on HIV. In 2014, there were more than 6,000 new cases of HIV in the UK. Men who have sex with men are most at risk of getting HIV, along with black African men and women born in sub-Saharan African countries.

You won't definitely get symptoms

If you have sex without a condom, the odds of catching an STI are increased. You can't tell by looking at someone whether they've got an STI or not.

These infections don't always have any symptoms, which means you might not even know if you've caught something. For example, around a quarter of people with HIV do not know they have it.

If you have an undiagnosed STI, you run the risk of not getting treatment and passing the infection on to others.

You can get an STI if you have sex only once

You only need to have unprotected sex once to get HIV or another STI, or pass one on to someone else. The more sexual partners you have, the more at risk you are. This is true whether you have more than one partner at the same time or at different times.

Where to get tested

If you think you might have an STI, including HIV, or are at risk of having one, you can get tested at a sexual health clinic or genitourinary medicine (GUM) clinic. Some community contraceptive clinics also offer STI testing.

Some HIV charities offer tests you can do at home. You can find out more about these from the Terrence Higgins Trust.

If you've started seeing someone new, or you and your partner want to stop using condoms, it is advisable to have a sexual health check.

Symptoms you might notice

If you notice anything different, contact a clinic straight away so you can be tested and treated for STIs.

Some symptoms you may notice include:

an unusual or smelly discharge

pain during sex

sores or rashes

irregular periods

People who have very recently been infected with HIV may have:

flu-like symptoms, such as a sore throat and fever

a rash on the chest

fatigue

nausea

diarrhoea

However, you might not have any symptoms – if you've had unprotected sex, get yourself checked. The sooner you're tested for an STI, the sooner it can be treated – and the sooner you can stop worrying about it.

Chlamydia

Chlamydia is the most commonly diagnosed STI in England. It is most common in men and women under 25, accounting for almost 138,000 new cases in 2014.

The National Chlamydia Screening Programme offers free chlamydia tests to as many under 25s as possible. These are available at young people's sexual health services and some pharmacies.

Most people with chlamydia have no symptoms, so they may not know they're infected. If left untreated, chlamydia can spread to other parts of the body, which can lead to long-term health problems such as infertility.

If you're under 25 and have had sex, you should be offered a test when you visit your GP, contraceptive clinic, or another health service. You can get tested in a range of places convenient for you. The test and any treatment you might need is free and confidential.

Your privacy

At the clinic, you can be sure of patient confidentiality. You don't have to give your real name, but make sure the clinic can contact you to give you the results of any tests. This can be done by letter, phone or text message, depending on the clinic.

A doctor or a nurse will ask you questions about your relationships and sexual partners, what contraception you use, and any relevant medical history. This is to help them work out what tests you need.

Getting the right treatment

Most STIs can be cured with antibiotics. Some, such as HIV, have no cure, but treatment can be given to stop it getting worse.

If you test positive for an STI, including HIV, staff at the clinic will explain your treatment to you and advise you on how to avoid infections in the future. Using a condom properly every time you have sex is the most effective protection against infections – get tips on using condoms.

If you have an infection, you'll need to tell anyone you've had sex with in the last six months so they can be tested, too. If you haven't had sex during this time, let your last sexual partner know. If you don't want to do this, the clinic can usually contact a partner (or ex) for you without mentioning your name.